Dan,

   I'm going to ask what might be an obvious question, is it SMOBC (Soldermask 
Over Bare Copper)? or did the surface layer get finished with tin/lead before 
soldermasking the fab? The only time I've ever experienced mask coming off in 
the wave was because of that. The plating is becoming liquidous and the mask 
loses it's adhesion. That's kinda' the direction I'm leaning because you say 
that the fab passes the tape test prior to wave.

   Let us all know if you figure it out, I'm a bit curious why that might happen
if it isn't a plating beneath the mask.



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#        Steve Gregory          #                                               
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     >We recently experienced soldermask peeling after wave from three different 
     >Fabricators all within 2 weeks. Subsequently we took sample lots of each 
     >Fabricator and performed a pre-wave and post-wave tape test. In all lots 
     >the boards passed pre-wave tape test but had a 10-25% failure post wave. 
     >What can cause this phenomena? Does the weather change have anything to do 
     >with soldermask application and durability?
     
     >Dan Hickey
     >Senior Buyer
     >Vicor 
     >[log in to unmask]

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